Acid Base Disorders

Question 1

Anion gap equation and normal value

Answer 1

Anion gap = Na - [Cl + HCO3]

8-12mEq/L

Question 2

Causes of high anion gap metabolic acidosis

Answer 2

MUDPILERS!
Methanol
Uremia
DKA
Polyethylene Glycol
Isoniazid
Lactic acidosis
Ethanol
Rhabdomyolysis
Salicylates

Question 3

Causes of normal anion gap metabolic acidosis

Answer 3

HARD UP!
Hyperalimentation
Acetazolamide
Renal tubular acidosis
Diarrhea

Uretosigmoid fistula
Pancreatic fistula

Question 4

ABG: pH 7.55 paCo2 52 HCO3 44

acidosis or alkalosis?
Metabolic or respiratory?
Compensation present?
Primary treatment?

Answer 4

alkalosis
metabolic, HCO3 is high
respiratory compensation by increased PaCO2
sodium chloride (if chloride responsive) responsive, acetazolamide if cannot tolerate fluids
MRA if chloride resistant

Question 5

ABG: pH 7.20 paCo2 25 HCO3 9

acidosis or alkalosis?
Metabolic or respiratory?
Compensation present?
Primary treatment?

Answer 5

acidosis
metabolic (bicarb is low)
respiratory compensation present with decreased PaCO2
alkali-therapy sodium bicarb

Question 6

Normal ABG?

Answer 6

7.4 / 40 / 80 / 24 / 97%

pH/PaCO2/PO2/HCO3-/SaO2

Question 7

How does metabolic acidosis cause hyperkalemia?

Answer 7

1. intracellular shift of H+ ions exchanges K+ to ECF

2. increased K+ reabsorption in renal intercalated cells

Question 8

Bicarb deficit equation

Answer 8

(0.5L/kg)(weight in kg)(24-measured bicarb)

Question 9

How do we correct emergent metabolic acidosis with bicarb?

Answer 9

Give HALF of the bicarb deficit IV over 0.5-4hours

Then remaining 50% po or IV over 1-2d

Question 10

How do we correct chronic metabolic acidosis with bicarb?

Answer 10

correct underlying cause

give 20-50% of bicarb deficit po TID for 3-5d

Question 11

Which of the following are adverse effects of sodium bicarb? (SATA)
A. belching
B. hyponatremia
C. flatulence
D. hyperkalemia

Answer 11

A. belching
C. flatulence

Metabolic acidosis cause HypERnatremia and HypOkalemia via intracellular shift of K+

Question 12

What do we base metabolic alkalosis treatment on and what are the treatment options?

Answer 12

Cl responsiveness
Cl <10mEq/L = chloride responsive (excessive diuretic use, nausea, vomiting)
- replete Cl with 0.9% NS
- acetazolamide if pt cannot handle fluids
Cl >20mEq/L = chloride resistant (excess mineralocorticoid activity)
- spironolactone (MRA)
- HCl or ammonium Cl for severe, non-responsive alkalosis

Question 13

Causes of respiratory acidosis (CO2 retention)

Answer 13

lithium, opiates, aminoglycosides, phenytoin
airway obstruction (asthma, COPD)
sleep apnea, tumors

Question 14

Treatment of respiratory acidosis

Answer 14

remove offending drugs (lithium, opiates, aminoglycosides, phenytoin)
if hypoxic admin O2
mechanical ventilation 
bronchodilators
**ultimate goal is to restore O2**

Question 15

Causes of respiratory alkalosis

Answer 15

anxiety, opiates, benzos

salicylates, catecholamines, theophylline, progesterone

Question 16

Respiratory alkalosis signs and symptoms

Answer 16

lightheaded, confused, syncope, N/V, renal compensation

Question 17

Respiratory alkalosis treatment

Answer 17

treat underlying (anxiety treatment, paper bag)
if hypoxic admin O2

Question 18

What is different about the timeline of respiratory compensation vs metabolic compensation

Answer 18

respiratory compensation within minutes

metabolic compensation takes days

Question 19

ABG: pH 7.26 paCo2 56 HCO3 24

acidosis or alkalosis?
Metabolic or respiratory?
Compensation present?
Primary treatment?

Answer 19

acidosis
respiratory
no, renal compensation is not present, bicarb is normal
underlying cause, oxygen, stop offending drugs